Iron in biological oxygen and redox transport serves energy supply roles essential to human health, work efficiency, and regulation of life processes. In the parallel mechanisms of biological nitrogen reduction, iron also serves in essential catalytic centers to provide important organic forms of nitrogen for growth via synthesis of cellular structures and catalysts for the maintenance of nutritive balance. Thus the details of biological metablism of the two major components of the atmosphere, O2 and N2, together with CO2, an essential but limiting constituent, must be understood and controlled to sustain human health. Concomitant metabolism of carbon skeletons control the recycling of known carcinogens, the refuse from animal and plant life, and the residues and by-products of industrial chemical technology. This proposal extends our earlier advances with iron proteins concerning the process and mechanism of O2 reduction with incorporation into organic molecules essential for cellular regulatory and energy release reactions. The methods evolved from our work in the Physics- Biochemistry-Genetics and interface continue to refine the precision of observation on the primary processes required to characterize the catalyses and the catalysts. The range of observation has proceeded over more than four orders of dynamic range to the microsecond time scale, temperatures from 4 to 350 degrees K, in aqueous media, mixed solvents and glasses. The separation of primary steps in electron tranport among 1 and 2 electron carriers and O2 will be a prime immediate focus with the iron centers (Fe2S2 Cys4) and P450 cytochromes as vehicles. A nontrivial, perhaps major, product of these researches is a new generation of motivated, competent investigators and leaders, highly educated and experienced in the biological probes to the problems of energy, information and regulation essential to life and to human health.